IAA-CSIC: Discovered the origin of the mysterious green ‘ghosts’ in the sky | Science

The late Hank Schyma, a Texan rock singer also known as Pecos Hank, perfectly remembers the day in which on camera he captured an unusual phantasmagoric image in the sky. It was May 25, 2019, when a giant storm hit Oklahoma. During just one mile, an extra green figure appeared at the top of the clouds, which he baptized ghost, a word that means ghost and is the acronym in English for “Green emissions of oxygen excited in the upper parts of a duende”. A team led by the Spanish engineer María Passas Varo has now discovered the authentic origin of these items espiritus in the sky: the presence of metals, above all the noise and noise, proceeding from the entry of dust interest in the atmosphere.

The mysterious ghosts are only a type of transitory luminous phenomenon. These optical events were detected early on the night of September 22, 1989, during a storm associated with a hurricane in the United States. As they were fleeting and short, the scientist Dave Sentman called them duendes, in the home of Puck, the strange characters of comedy Sound of a true night, by William Shakespeare. Indeed, numerous transitory luminous phenomena have been described, always with imaginative names. The elves are shining similar to a ring. The trolls are purple chorros. The duendes are flashes of red color, sometimes in the shape of a jellyfish. And the ghosts are green lights that, on exceptional occasions, emerge at the end of the events.

María Passas Varo and her colleague Justo Sánchez del Río, at the Calar Alto observatory, in Almería.IAA/CSIC

María Passas Varo works at the Instituto de Astrofísica de Andalucía (CSIC), in Granada, the city where she was born for 43 years. She still remembered with enthusiasm the day she learned that the singer and singer Hank Schyma had discovered a new transitory luminous phenomenon. Passas Varo and her colleague Justo Sánchez del Río have designed an instrument to analyze the colorful and fleeting electrical discharges that appear above some storm clouds, at an altitude of between 40 and 90 kilometers. In June 2019, Spanish scientists decided to use sophisticated herbs to try to create a green ghost in Spanish skies.

The instrument is located on the terrace of the house of Oscar van der Velde, a Dutch meteorologist from the Polytechnic University of Cataluña who lives in the Barcelona area of ​​Castellgalí. El desafío era mayúsculo. “The ghosts are superinfrecuentes. From every 100 duendes a ghost rises”, subraya Passas Varo. His device automatically points to the area of ​​the sky where there are large storms, thanks to the real-time consultation of the data base of the State Meteorology Agency. Finally, on September 21, 2019, the team detected a red duende in the shape of a jellyfish during a storm over the Mediterranean Sea. First of all, a green ghost fugaz.

Instrument installed on the terrace of a living room in the Barcelona area of ​​Castellgalí.Oscar van der Velde

The British photographer Paul Smith defines himself as a “cazador de duendes”. His colleague Hank Schyma consulted her immediately if that phantasmagoric green light over Oklahoma was normal. Smith thought it might be a camera error, but patiently reviewed his own recordings and discovered several similar luminous phenomena. Juntos decided to give her a name. Smith recognizes that they have come across several days trying to spell out the acronym goblinslike the creature of European folklore, but like no other Schyma acabó proposing ghost, with this intuition that there were green emissions from the excited oxygen. “I theorized that this green color must have some type of oxygen participation, such as nightlight and auroras,” notes Smith.

The results of the Passas Varo analysis were a surprise. “Our instrument has an spectrograph, it is not a normal camera. It’s like the record holder The Dark Side of the Moon of Pink Floyd, in which a prism appears to which the white light connects and separates the electromagnetic spectrum in the absence of all colors. Nosotros hacemos lo mismo. We separate the light that brings us and see what chemical elements are involved in the process,” explains the telecommunications engineer. “The surprise was that there was oxygen, but very little. The most there is is hierro,” she says. Your results are published this Tuesday in the magazine Nature Communications.

Compound and colorful image of the duende rojo captured on 21 September 2019 from Castellgalí, where a green ghost was detected.IAA/CSIC

The new conclusions may explain why green ghosts are so infrequent in the skies. In four years of observation, Spanish scientists have only created one. “We did not hope that there would be so much hierro density at this altitude. The meteors that enter the atmosphere at great speed rise, if they leave and the metal atoms that are suspended. The hierro’s head is normally a little higher. In our case, we put forward the hypothesis that on that day there would be waves of gravity (a wave phenomenon in the air) and the head of the lower head,” notes Passas Varo.

The Spanish study is the first scientific publication on green ghosts. Hank Schyma and Paul Smith learned in 2019 about physics Burcu Kosar, an expert in transient luminous phenomena who works at NASA. A little over a year ago, the state-owned space agency launched Spritacular, a program that encourages citizens to watch duels, trolls, elves, ghosts and other creatures from the “electric zoo”, in Kosar’s words. Physics seeks to create a basis of world data that allows us to resolve the enigmas that arise in the specters of the heavens: How often does it happen? Why adopt these forms? What atmospheric conditions will open?

These phenomena are difficult to observe at a simple glance, but on occasion they have been confused with anything, as a NASA informant noted in September. María Passas Varo’s team proposes a more pedestrian explanation: an electrical phenomenon associated with an anomalous noise in the upper reaches of the atmosphere. “They are lights in the sky that have a very rare form, which we are not used to seeing. It seems alien, but it isn’t,” says the investigator.

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